'********************************************************************* ***************
' Creates a pseudo Transparent looking set of tabs based on the colour
' that was choosen as a background
'********************************************************************* ***************

You fill the entire tab area twice and it causes the flicker. When it really looks like you only want the area where the tabs will be inserted to be colored differently, not the entire tab area. If you want the entire tab are, then I guess you might have to live with the flicker.